Continuity mistake: In the season 5 episode 'Destiny' we see that the first time Angelus meets William, he has already adopted a more cockney accent, but in an earlier episode of BtVS (Fool For Love) Angelus asks Spike "Since when do you talk like that", suggesting he changed his accent after they met.

Angel (1999)
1 continuity mistake in Season 5 generally
Visible crew/equipment: When Angel is fighting the demon, you can see an obvious camera and two hands in the bottom right corner. (00:27:10)
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Answer: Everybody including Angel saw her. After helping them and then being left alone to talk to Angel, Cordelia says that the Powers That Be let her come back one more time to help them. After Angel gets a call saying that she died, he realises that it was her spirit that was helping them the entire time.